Why CNCF Recommends Apache-2.0

The Cloud Native Computing Foundation (CNCF) believes that the best software license for open source projects today is the Apache-2.0 license (Apache-2.0). Our goal is to enable the greatest possible adoption of our projects by developers and users. Our larger goal with CNCF (and with the Linux Foundation, of which we are part) is to create an intellectual property “no-fly zone”, where contributors and users can come together from any company or from no company, collaborate, and build things together better than any of them could do on their own.

We think that permissive software licenses foster the best ecosystem of commercial and noncommercial uses by enabling the widest possible use cases. A report this month from Redmonk shows the increasing popularity of these permissive licenses. Proponents of copyleft licenses have argued that these licenses prevent companies from exploiting open source projects by building proprietary products on top of them. Instead, we have found that successful projects can help companies’ products be successful and that the resulting profits can be fed back into those projects by having the companies employ many of the key developers, creating a positive feedback loop.

In addition, Apache-2.0 provides protection against a company intentionally or unintentionally contributing code that might read on their patents, by including a patent license. We believe that this patent protection removes another possible barrier to adoption and collaboration. Our view is that having all CNCF projects under the same license makes it easier for companies to be comfortable using and contributing, as their developers (and those developers’ attorneys) do not need to review a lot of licenses.

Of course, many CNCF projects also rely on libraries released under other open source licenses. For example, Linux underlies the entire cloud native platform and git is the software development technology of choice for all of our projects. Both are licensed under GPLv2 (and both were originally authored by Linux Foundation Fellow Linus Torvalds). The CNCF projects themselves are currently mainly written using the open source programming languages Go (BSD-3), Ruby (BSD-2) and Scala (BSD-3).

Let’s now look at the CNCF policy for projects. For an Apache-2.0-licensed project to be accepted into the CNCF, it requires a supermajority vote of our Technical Oversight Committee (TOC). For a project under any other license, it would require both a supermajority TOC vote and a majority vote by our Governing Board. While this may occur in the future, our strong preference is to work with prospective projects to relicense under the Apache-2.0. Let’s look at two example projects to see how this can work.

We’re currently having conversations with gRPC, which is licensed under the BSD-3 license plus a patent grant. When combined with the patent license in Google’s Contributor License Agreement (CLA), this combination of BSD-3 + patent grant + CLA is quite similar to Apache-2.0, in that it combines a permissive copyright license with patent protections. However, Apache-2.0 is a better-known and more familiar license, and so it accomplishes similar goals while likely requiring less legal reviews from new potential gRPC users and contributors.

Separately, we’ve also been talking with GitLab, which uses the same MIT license as its underlying framework, Ruby on Rails. Although it’s natural to go with the same license as Rails and Ruby, we are working with the gitlab team to investigate whether it would be feasible to relicense to Apache-2.0 for some or all of their codebase. The main advantage of doing so would be the additional patent protections so that companies would be confident in their ability to contribute and use the software without later being accused of violating the patents of other contributors.

In closing, we’d like the acknowledge the debt of gratitude we have for the work done by the authors of these licenses, especially the Apache Software Foundation, and of course all the developers who write the software to make these licenses useful.